Farmers from Tami Nadu demonstrate in Delhi with what they say are the bones of farmers who committed suicide because of a crippling drought and high debt.
Photograph: Julian Chung for the Guardian

Climate change may have contributed to the suicides of nearly 60,000 Indian farmers and farm workers over the past three decades, according to new research that examines the toll rising temperatures are already taking on vulnerable societies.

Illustrating the extreme sensitivity of the Indian agricultural industry to spikes in temperature, the study from the University of California, Berkeley, found an increase of just 1C on an average day during the growing season was associated with 67 more suicides.

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An increase of 5C on any one day was associated with an additional 335 deaths, the study published in the journal PNAS on Monday found. In total, it estimates that 59,300 agricultural sector suicides over the past 30 years could be attributed to warming.

Temperature increases outside the growing season showed no significant impact on suicide rates, suggesting stress on the agriculture industry was the source of the increase in suicides.

Also supporting the theory was that rainfall increases of as little as 1cm each year were associated with an average 7% drop in the suicide rate. So beneficial was the strong rainfall that suicide rates were lower for the two years that followed, researcher Tamma Carleton found.

Farm sector suicides in India decreased last year, but remain at epidemic levels in some states and are a source of immense pressure on legislators.

Tamil Nadu is suffering its worst drought in 140. Protestors claim it has triggered hundreds of suicides. Photograph: Julian Chung for the Guardian

“He had talked about things like this [suicide] happening with others, but never about doing it himself,” she said.

The next week, Radhakrishnan and her daughter-in-law stood outside the bank brandishing wads of rupees. “We told them, we have repaid your money, now will you give us back my husband’s life?” she said.

Last year the Indian government launched a £1bn insurance scheme to protect against crop failures and try to halve farmer and farm worker suicides.

Maharashtra, Punjab and the country’s most populous state, Uttar Pradesh, have all passed farm-debt waivers at enormous cost to the public purse to appease the demands of the agricultural sector, which commands strong political sway.

Carleton said her research showed little evidence Indian farmers were changing their practices to accommodate rising temperatures.

“Without interventions that help families adapt to a warmer climate, it’s likely we will see a rising number of lives lost to suicide as climate change worsens in India,” Carleton said.

The true suicide rate was probably higher, she added, because deaths are generally underreported in India and, until 2014, suicide was considered a criminal offence, discouraging honest reports.

“The tragedy is unfolding today,” she said. “This is not a problem for future generations. This is our problem, right now.”

•In the UK, the Samaritans can be contacted on 116 123. In the US, the National Suicide Prevention Hotline is 1-800-273-8255. In Australia, the crisis support service Lifeline is on 13 11 14. Helplines in other countries can be found here